Greater political and social freedoms, instituted by the last Soviet leader, Mikhail Gorbachev, created an atmosphere of open criticism of the Moscow regime. The dramatic drop of the price of oil in 1985 and 1986, and consequent lack of foreign exchange reserves in following years to purchase grain profoundly influenced actions of the Soviet leadership.
Several Soviet Socialist Republics began resisting central control, and increasing democratization led to a weakening of the central government. The USSR's trade gap progressively emptied the coffers of the union, leading to eventual bankruptcy. The Soviet Union finally collapsed in 1991 when Boris Yeltsin seized power in the aftermath of a failed coup that had attempted to topple reform-minded Gorbachev.